益生菌发酵对红枣汁抗氧化活性、营养品质及香气的影响

选取6种商业益生菌分别对红枣汁进行发酵,研究其对红枣汁的抗氧化活性、理化指标及香气的影响。结果表明,益生菌发酵可显著提高红枣汁的抗氧化能力,果321复合菌发酵枣汁的DPPH自由基清除能力最强,为573.83 mg/L,而植物乳杆菌（Lactobacillus plantarum）发酵枣汁的ABTS自由基清除能力最强,为1 034.00 mg/L,瑞士乳杆菌（Lactobacillus helveticus）发酵枣汁的铁离子还原力（FRAP）值最高,为1 366.34 mg/L。瑞士乳杆菌的产酸性能较好,发酵后产乳酸量约0.45 mg/L,总多酚和总黄酮含量分别较红枣汁提高了2.94%和2.85%。电子鼻分析结果表明,益生菌发酵可显著改变红枣汁的香气成分,且线性判别分析（LDA）对红枣汁香气物质的区分和识别效果优于主成分分析（PCA）,发酵红枣汁的特征风味主要来源于硫化物、萜烯类、广谱甲基类、氮氧化物、乙醇和芳香型化合物。     

Isolation and identification of a bacterial cellulose synthesizing strain from kombucha in different conditions: <Emphasis Type="Italic">Gluconacetobacter xylinus</Emphasis> ZHCJ618

A bacterial cellulose (BC) synthesizing strain (Gluconacetobacter xylinus ZHCJ618) was isolated from kombucha and selected as the species for commercial applications owing to its high phenotypic stability and sustainable production capacity of 7.56 ± 0.57 g/L under static culturing conditions and 8.31 ± 0.79 g/L under shaking conditions. The morphological, physiological and biochemical characteristics of the strain were similar to those of Gluconacetobacter genus. The 16S rDNA sequence homologies with G. xylinus NCIB 11664 reached 99%, showing that the isolated strain can be identified as G. xylinus. The material properties of BC were studied by fourier transform infrared spectroscopy, scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, and tensile test. The results showed that BC synthesized under static conditions exhibited stronger tear strength, higher crystallinity, superior waterhold and rehydration rate than BC synthesized under shaking conditions.     

3．0Mt／a重催装置余热锅炉现状及节能技术改造

兰州石化公司炼油厂3．0Mt／a重油催化裂化装置的两台余热锅炉在运行中存在烟气侧运行阻力大、排烟温度高、省煤器给水入口温度低、存在尾燃等问题。采用翅片管结构省煤器、提高助燃空气温度、改造燃烧器、布置正压防爆固定旋转式蒸汽吹灰器对余热锅炉进行节能技术改造。改造后,两台锅炉炉膛压力分别由改造前的2.8kPa和2.7kPa降到1.9kPa和1.8kPa,余热锅炉烟气侧阻力降低;锅炉排烟温度由300℃降到205℃,烟气热量利用率和锅炉热效率得到提高;增设给水预热器后,省煤器给水温度及出水温度分别提高到150℃和240℃,外取热器及油浆蒸汽发生器多产蒸汽10t/h,两台锅炉总产汽量增加了60t/h,产生效益1908.42万元。     

新型吸收剂在湿法烟气脱硫中的应用

SO2是现今主要的大气污染物,而我国以煤为主要燃料的特点使SO2的污染日益严重。因此,控制SO2的排放,积极应用二氧化硫控制技术,对改善大气污染状况至关重要。介绍了传统的石灰石一石膏法,探讨了硫酸亚铁法、有机胺法、尿素法、亚硫酸钠循环法、柠檬酸钠循环法、过氧化氢法等应用新型吸收剂的湿法烟气脱硫技术,并对它们的优缺点做了简单评述。     

Electrochemical synthesis and characterization of a novel thiazole-based copolymer and its application in biosensor

A novel copolymer based on 2-aminothiazole (AT) and 2-amino-4-thiazoleacetic acid (ATA) is electrochemically synthesized and then characterized using UV–visible absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and electrochemical techniques. The results confirmed that the obtained polymer was a copolymer rather than a blend or a composite of the respective homopolymers and could improve the electrochemical response of both positively and negatively charged analytes. Therefore, the copolythiazole film was applied to determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). It is found that the peak separating degrees and peak currents of AA, DA and UA at copolythiazole modified electrode were much better than those at bare GCE. Under the optimum conditions, the linear calibration curves were obtained in the range of 10–2000 μM for AA, 1–150 μM for DA, 1–180 μM for UA. The detection limits of AA, DA and UA were 2, 0.04 and 0.4 μM, respectively (S/N = 3). The practical application of the modified electrode was demonstrated by the determination of UA in urine sample.     

给建筑一个环境--西安千年文化商业街设计

本文强调回到地域本身寻找地方特色和建筑个性,拒绝通过模仿古代建筑细节来暂时获得风格与形式上的“和谐”。方案设计借助西安黄土台地的多层高差跌落,采用半下沉的场处理方式,强调场、院、井、巷的空间体验,形成一片绿色,一串场院,一种体验的效果,最终,使千年文化商业街获得与兵马俑景观和西乡士建筑风格的本质意义上的和谐与统一。     

退火温度对Ba_(0.6)Sr_(0.4)TiO_3薄膜晶化及介电性能的影响

用改善的溶胶凝胶(Sol-Gel)法制备了钛酸锶钡(Ba_0.6Sr_0.4TiO_3, BST)薄膜,研究了退火温度对薄膜晶化及介电性能的影响.X射线衍射表明,由于薄膜较薄,各温度下衍射峰强度均微弱,但呈(110)择优取向,随温度的升高峰强度逐渐增加,也出现其他晶向的衍射峰.扫描电镜和原子力显微镜表明,改善的BST薄膜表面形貌光滑致密、无裂纹、无缩孔,随温度的升高薄膜晶化增强、晶粒逐渐长大、粗糙度增加.40 V外加电压下的介电性能大幅度提高,介电调谐率大于30%,介电损耗约0.02,其中,650 ℃对应介电调谐率45.1%和介电损耗0.0187.同时,就有关结构、介电性能及退火温度的关系进行了讨论.     

圆管无芯弯曲壁厚变薄量研究

采用回归分析和曲线拟合方法，提出圆管无芯弯曲壁厚减薄量新的计算公式。经验证该公式比目前实际采用的变薄量计算公式具有更高的计算精度。     

电磁辐射防护材料人体防护性能评价研究

本文采用高分辨率人体电磁辐射模型和非均匀网络时域有限差分法(FDTD),通过比较人体模型在防护前后全身平均比吸收率SAR的变化,建立了防护材料对人体防护性能的评价方法。利用此方法,针对不同频率、不同入射角度的电磁辐射,对不同防护材料的防护性能进行了评价。结果表明,防护材料的防护性能并不仅仅取决于其屏蔽性能,还与防护方式、照射方式等密切相关。局部防护方式对被防护的器官有良好的防护效果。相对于水平照射,斜向上照射时,防护效果较差;斜向下照射时,防护效果较好。     

消息保密的代理签名方案的安全性分析与改进

通过对一种消息保密的代理签名方案进行安全性分析,发现原始签名人和盲签名的接收者可以在互不泄漏对方秘密的情况下合谋篡改待签名的消息并伪造代理签名,并且代理人可以滥用代理权。为此,通过将代理签名密钥转换为Schnorr签名,并利用授权证书给出了改进方案,可防止代理人滥用代理权和抵制原始签名人和盲签名的接收者合谋攻击,克服了这种方案的缺点,同时具备这种方案的其它安全性要求。